Why has no nominee put forth like 3 names from his shortlist to the convention and allowed the delegates to vote for the VP nominee? That’d be some great drama for the networks and generate a lot of coverage of the proceedings.
The last one to let the party pick his running mate was Adlai Stevenson, IIRC, and that was back when the ticket required balance between the northern and southern wings and one couldn't be trusted to sate the other. I guess the party doesn't want to be accused of smoke-filled rooms, however true those accusations.